A liquid droplet ejection apparatus for ejecting ink from an ejection head provided in the liquid droplet ejection apparatus and forming an image on a recording medium by the ink impinging on the recording medium such as a paper has been conventionally known. The liquid droplet ejection apparatus supplies the ink from an ink tank for storing the ink to the ejection head through a tube. If there are bubbles in the ink at supplying the ejection head with the ink, it is difficult to eject the ink, thereby reducing the recording quality of the recording medium. Therefore, it is necessary to remove bubbles that entered a passage (hereinafter, called as “a liquid supply flow passage”) for flowing liquid from the ink tank to the ejection head. As a structure of removing bubbles that entered the liquid supply flow passage, a structure described in Japanese Patent Application Laid-Open No. 2008-18589 has been known. In the structure described in Japanese Patent Application Laid-Open No. 2008-18589, a bubble storage chamber for storing bubbles is provided in the liquid supply flow passage and the bubbles stored in the bubble storage chamber are discharged to an outside of the bubble storage chamber by a vacuum pump. In the structure described in Japanese Patent Application Laid-Open No. 2008-18589, a valve is provided in a passage hole for connecting the bubble storage chamber and the outside. The valve changes its position along the passage hole. The valve is positioned at a position of opening the passage hole if discharging the bubble storage chamber, while the valve is positioned at a position of covering the passage hole if not discharging the bubble storage chamber. The opening and closing of the bubble storage chamber is performed by the valve.